Seahorse Erectus Hippocampus Erectus

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Lined Seahorse (Hippocampus erectus)

(Also known as the Northern Seahorse or Erectus Seahorse)

Overview

The Lined Seahorse is one of the most recognisable and popular seahorse species in the aquarium hobby. It displays a distinctive lined pattern along its body, varying in colour from brown and yellow to orange, red, or even black depending on mood and environment. Growing to about 15–18 cm (6–7 inches), H. erectus is hardy compared to many seahorses and well-suited to dedicated, species-specific aquariums. Known for their gentle, graceful nature, seahorses use their prehensile tails to anchor to objects while hunting for small prey.

Origin

Native to the Western Atlantic Ocean, ranging from Nova Scotia and the Gulf of Mexico to the Caribbean and Brazil. Found in seagrass beds, mangrove roots, and coral rubble zones, often in calm, shallow coastal waters.

Feeding

The Lined Seahorse is a carnivorous ambush predator, feeding on small, live prey in the wild. Captive-bred individuals are easier to feed and usually accept frozen foods. Ideal diet includes:

• Frozen mysis shrimp (staple food)

• Enriched brine shrimp (supplementary only)

• Live copepods or amphipods for enrichment

• Occasional live mysis shrimp for variety

Feed 2–3 small meals daily. Target feeding with a turkey baster or feeding station helps ensure they get enough food. Avoid strong flow areas during feeding.

Tank Mates

Seahorses are peaceful and slow-moving, requiring equally calm tank mates that won’t outcompete them for food. Ideal companions include:

• Pipefish and dragonets (with care)

• Small gobies and blennies

• Firefish and cardinalfish

• Cleaner shrimp and other gentle invertebrates

Avoid aggressive or fast feeders (e.g., clownfish, Wrasses, tangs, triggers, or dottybacks).

Aggression

Completely peaceful. Seahorses form strong pair bonds and display courtship dances. Males carry the eggs in a brood pouch until giving birth to fully formed young. They should be kept singly, in pairs, or in small groups of similar size and species.

Experience Level

Intermediate to advanced. Captive-bred H. erectus are hardy and recommended for aquarists experienced with maintaining stable marine systems. They are sensitive to strong currents, poor water quality, and aggressive tank mates.

Water Parameters

• Temperature: 22–26°C (72–79°F)

• pH: 8.1–8.4

• Salinity: 1.020–1.025 SG

• Hardness (dKH): 8–12

• Tank Size: Minimum 30 gallons (115L) for a pair; 50+ gallons preferred for groups

Provide low to moderate flow, with hitching posts (macroalgae, gorgonians, or artificial coral branches) for them to grasp with their tails.

Reef Compatibility

Reef safe with caution. Seahorses will not harm corals or invertebrates, but they do best in peaceful, soft coral or macroalgae setups with no stinging corals (avoid anemones, large euphyllias, or hydroids).

Above images for illustration purposes only. Exact colours, patterns, and size may vary between individuals.

Please note: The livestock that is sold on our online site is not held in store at our Swell shop, or available for collection from the shop. Species sold at our Swell store will differ from ones available to order to your door.

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